Thermoplastic sheets, composite laminate and other similar molding material sheets that can be cured into hardened panels are often used in fabricating contoured body panels of products such as automobiles, boats and other products having bodies with smooth contoured surfaces. In molding sheets of this type, it is common practice to use a tool or solid mold that has a single surface with the desired shape and contours of the body panel to be fabricated. To achieve the desired shape and contours of the body panel, the solid mold surface must have substantially the exact same shape and contour desired for the body panel. It is common practice that a prototype body panel first be produced having the desired shape and contours of the final body panel. From the prototype body panel a solid mold is produced based on the shape and contours of the prototype. The solid mold can be produced by hand crafting or machining the mold surface on a solid material or by other similar known methods. All of these methods typically require substantial amounts of materials and are time consuming and therefore expensive. The mold will then be used to form thermoplastics sheets, composite laminate sheets or other similar molding material sheets into the desired final body panel.
There are often many difficulties encountered in producing a solid mold having a surface that in turn will form molding material sheets into the desired shape and contours of the final body panel. For example, in drape forming or molding of high temperature thermoplastics on a solid mold surface, there is a large degree of shrinkage of the thermoplastic sheet after the sheet has been molded on the mold surface and the sheet cools. Additionally, in molding the sheets of thermoplastics or composite laminates on a solid mold surface, it is often very difficult to completely engage the sheet material with the mold surface so that the sheet material stays in the desired shape and contour sought for the final molded body panel. As a result, it is often the case that the initial mold produced to achieve the desired final shape and configuration of a body panel may not achieve satisfactory results, requiring a further mold or molds to be produced before the sheet molding process achieves the desired shape and configuration of the body panel product. The need to produce several molds before arriving at the mold that will produce the desired shape and contours of the final body panel product is very time consuming and expensive.
The current practice of producing solid molds involves cutting the mold surface from a block of material using a computer numerical control (CNC) machine. The cut mold surface would then be finished in order to prepare the surface that will shape the molding material sheets and release the cured sheets properly. Again, this process of forming the molds is time consuming and costly. Many times the mold will have to be reconstructed and modified in order to gain acceptable quality in the shape and contour of the final product. Furthermore, if variations are made to the design of the final product in the development process of the product, the mold for that product must be either modified or completely remade. Again, this is especially difficult when the products to be made are low volume products, as is often the case in the art of forming thermoplastic or plastic composite replacement body panels.